Mark 15.5 rebreather

I still believe that the Mark 15 is the finest, most engineered, most
tested rebreather in the world, bar none. Mostly due to the
conversations on this list as to why the Mark 15 Series rigs are the
best rigs for everyone to use, and how by simply buying one, you begin
to look like a Greek God with chiselled features that make women swoon
at the sight of you and your manly rebreather, and also the
conversations about how extended use of Cis Lunars, or Inspirations can
cause gonad atrophy, loss of chest hair, sagging buttocks, and a
general repulsion of most members of the opposite sex. So I decided in
the general interest of those who wish to regain their youthful vigour
by investigating thoroughly these magic machines which bestow such
virility on their owners, to publish a list of comparisons of these
magnificent units. All those who read and memorize these pages will find
a new robustness in their demeanour which will bring a twinkle of
anticipatory elation to the eyes of all women they meet, and a knowing
smile from other valorous men who too have heard the Word, and seen
the Way. And those who actually own and dive a Mark 15 Series
Rebreather already know the satisfaction of Crushing their Enemies,
Seeing them Driven Before You, and Hearing the Lamentations of their
Women... Kevin Juergensen

China Cave Exploration

In December 2013 Harry was fortunate enough to be invited by
the Department of Tourism in Du An County, Guangxi Province China, to
experience the amazing new cave diving sites on offer and celebrate the
opening of the Du An diving Centre. It was an extraordinary trip with
the Chinese being generous and wonderful hosts, and the diving was
UNBELIEVABLE! Literally hundreds of unexplored karst features litter the
beautiful mountains and the sport was just in its infancy in China.

Significant
credit must go to the French cavers (Bulles Maniacs) in particular
Pierre Eric Deseigne, and also the Australian GUE divers who have done a
lot to lay the ground work for us to follow. Have a look at their sites for more info: www.expeduan.org and http://nkpp.org/duan/

So in March 2015 following Oztek in Sydney, the Wetmules ventured into the south of China to do some exploration of their own...

Daxing Spring with mist on the karst towers.

With nearly two weeks of exploration ahead, the first decision was which caves to dive? We have a strong interest in deep cave exploration so Daxing Spring and Jellyfish Cave were selected as the main targets, with the team splitting into two. Dave Hurst, Dave Bardi and Sandy Varin would look at Jellyfish and Harry and Craig Challen would look at Daxing. March had been chosen as the best time for exploration as visibility was rumoured to be at its best just before the wet season, although if the rains came early we would be in strife! A trip to Jellyfish showed that the dry season had played an unexpected trick on us; the water was so low that access to the water was impossible without ropes or ladders. The stone stairs were many metres above the water! So all attention turned to Daxing.

Daxing (Dah-shing) is a major spring north of Du An and is the source of a significant river.

Daxing Spring and river outflow (Google Earth)

Arrows indicate location of North and South entrances to cave system.

With water temperature of 20-21 degrees C and reasonable visibility (5-10m) we started diving the two main entrances to this massive site. Both south and north entrances have been dived to depths of 155m (Pe Designe, France) and 164m (Mia Pietikainen, Finland and Pascale Bernabe, France) respectively so we were keen to push and map the cave further. We were all diving twin rebreather systems so were not reliant on large support teams or staging multiple bailout cylinders in the cave...the perfect solution in our view to deep diving with limited resources. The Du An diving centre had all the cylinders, weights and gas we needed and food and accommodation in Du An is very reasonable.

Dave, Dave and Sandy tooling up for a big one! Everyone is diving twin rebreather systems.

Craig and I focussed on the south entrance and over a few days diving worked our way down from the end of the existing line at 154m to 203m. The shaft in Daxing South is the most perfectly vertical wall I have ever dived in a cave. You can literally free fall straight down from 65m to well over 200! The wall to the north side of the shaft disappears at around 116m and we ran a line from the shaft at this point, over to the north side of the cave thus establishing a traverse at a depth of 118m. This was a particularly satisfying dive and very exciting to see the other line come into view. It will be a thrill for future divers to swim down one side and come up on the other.

Harry and Craig at Daxing. During deco in the north entrance one can read the big sign saying "Welcome to Diving Paradise"!

On the north side, Dave, Sandy and Dave worked their way down the slightly more sloped tunnel to the end of Mia's line at 164m and beyond. A cave adapted fish was seen at a depth of 133m on the north side and a strong outflow of water could be felt at the slightly restricted passage around 45m.

As with many visiting divers in China, we worked a lot with the locals to help them learn more about technical diving, diving safety and risk management. Mia Pietikainen and I ran a workshop for the dive shop staff concentrating on recognising and looking after sick or injured divers. Also, Craig and I visited the hyperbaric chamber in Du An and talked to the staff about treating divers with decompression sickness. The chamber seems like a reasonable facility but not surprisingly they have not seen many divers!

Craig chats to the chamber operator at Du An hospital.

And Harry gets fitted up for an oxygen mask

Ultimately, dives were performed to exactly 213m on both sides of the cave by the team and no sign of the bottom of the cave was seen. A dropline from the middle of the traverse demonstrated a floor at 151m giving the impression of a large saddle separating the two sides. One wonders if below the saddle, there is a single massive void connecting into the mythical underground rivers of Du An! Perhaps on our next trip to China we will find out the answer :-)

A sketch of the cave at the end of the trip.Six dives to over 200m, and multiple other dives in the 100-160m range were performed in 10 days without serious incident